Exoscope with enhanced depth of field imaging

ABSTRACT

An exoscope with enhanced depth of field imaging is provided. The exoscope includes first and second sets of optical devices, the first set having a fixed image plane, the second set having a variable image plane adjacent the fixed image plane of the first set. The second set includes at least one variable device configured to change the position of the variable image plane. A beamsplitter splits light from a combined optical path of the first and second set to respective image devices of the first and second set of optical devices. A controller controls the at least one variable device to change the position of the variable image plane relative to the fixed image plane, combines images acquired by the respective image devices, and controls a display device to render a combined image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/053,298 filed Aug. 2, 2018, the contents which are incorporatedherein by reference.

FIELD

The specification relates generally to exoscopes and specifically anexoscope with enhanced depth of field imaging.

BACKGROUND

A surgical microscope is an essential tool in many surgical proceduresincluding those in spine and brain. With advances in optics and thedigital microscope, surgeons are now operating with more visualizationpower, including higher resolution and higher magnification, allowingsurgeons to see finer details in the surgical field. However, there isone fundamental trade-off in any surgical microscope: the higher themagnification and optical resolution that the surgeon utilizes, thesmaller the depth of field (i.e. smaller the field of focus in the depthdirection). This is problematic as surgeons require anatomical landmarksin the vicinity of the surgical site to be in focus to provide depthcues and context while operating.

SUMMARY

The present disclosure is generally directed to an exoscope withenhanced depth of field imaging. The exoscope provided herein includestwo optical paths that image the same region of a sample, for exampletissue. A first optical path has a fixed optical path length and hence afixed image plane and fixed depth of field, while the second opticalpath has a variable optical path length and hence a variable image planeand a variable depth of field. The two optical paths partially overlapusing a beamsplitter. The variable optical path length may be achievedusing a varifocal lens, such as a liquid-based varifocal lens and/or amoveable plenoptic array of lenses and/or an optic wheel and/or amoveable lens and/or a moveable sensor. Images from the two opticalpaths are combined and rendered at a display screen.

Hence, the techniques described herein are generally compatible withimage guided medical procedures using an access port. This port-basedsurgery approach allows a surgeon, or robotic surgical system, toperform a surgical procedure involving tumor resection in which theresidual tumor remaining after is minimized, while also minimizing thetrauma to the intact white and grey matter of the brain. In suchprocedures, trauma may occur, for example, due to contact with theaccess port, stress to the brain matter, unintentional impact withsurgical devices, and/or accidental resection of healthy tissue. Thetechniques described herein may assist a surgeon performing brainsurgery, and the like, via an access port in determining locations oforganized tissue in a brain.

Provided herein is an exoscope comprising: a first set of opticaldevices, forming a first optical path having a fixed path length and afixed image plane, including a first image detector configured toacquire a first image at the fixed image plane; a second set of opticaldevices, forming a second optical path having a variable optical pathlength and a variable image plane adjacent the fixed image plane of thefirst set of optical devices, the second set of optical devicesincluding: a second image detector configured to acquire a second imageat the variable image plane; and at least one variable device configuredto change a length of the variable optical path length and position ofthe variable image plane relative to the fixed image plane; abeamsplitter positioned in both the first optical path and the secondoptical path, the beamsplitter configured to: combine the first opticalpath and the second optical path between the beamsplitter and both thefixed image plane and the variable image plane; and direct respectivelight from each of the first optical path and the second optical pathrespectively towards the first image detector and the second imagedetector; a display device; and a controller configured to: control theat least one variable device to change the length of the variableoptical path length and the position of the variable image planerelative to the fixed image plane; control the first image detector toacquire the first image at the fixed image plane; control the secondimage detector to acquire the second image at the variable image plane;generate a combined image of the first image and the second image; andcontrol the display device to render the combined image.

BRIEF DESCRIPTIONS OF THE DRAWINGS

For a better understanding of the various implementations describedherein and to show more clearly how they may be carried into effect,reference will now be made, by way of example only, to the accompanyingdrawings in which:

FIG. 1 shows an example operating room setup for a minimally invasiveaccess port-based medical procedure, according to non-limitingimplementations.

FIG. 2 is an example illustration of a medical navigation system thatmay be used to implement a surgical plan for a minimally invasivesurgical procedure, according to non-limiting implementations.

FIG. 3 depicts a block diagram illustrating components of a planningsystem used to plan a medical procedure that may then be implementedusing the navigation system of FIG. 2, according to non-limitingimplementations.

FIG. 4 depicts an example implementation port based brain surgery usinga video scope, according to non-limiting implementations.

FIG. 5 depicts insertion of an access port into a human brain, forproviding access to interior brain tissue during a medical procedure,according to non-limiting implementations.

FIG. 6 depicts a side schematic view of an exoscope with enhanced depthof field imaging, and an optical path of a first set of optical devices,according to non-limiting implementations.

FIG. 7 depicts the exoscope of FIG. 6, and an optical path of a secondset of optical devices in a parallel plane mode, according tonon-limiting implementations.

FIG. 8 depicts the exoscope of FIG. 6, and an optical path of the secondset of optical devices in a lens mode, according to non-limitingimplementations.

FIG. 9 depicts image planes of the exoscope of FIG. 6, according tonon-limiting implementations.

FIG. 10 depicts a schematic block diagram of a controller of theexoscope of FIG. 6, according to non-limiting implementations.

FIG. 11 depicts an exoscope similar to the exoscope of FIG. 6, adaptedto include optical filters, according to non-limiting implementations.

FIG. 12 depicts an exoscope similar to the exoscope of FIG. 6, adaptedto include a moveable lens, according to non-limiting implementations.

FIG. 13 depicts an exoscope similar to the exoscope of FIG. 6, adaptedto include a moveable image detector, according to non-limitingimplementations.

FIG. 14 depicts a three-dimensional image detector that includes twoexoscopes similar to the exoscope of FIG. 6, according to non-limitingimplementations.

DETAILED DESCRIPTION

Various implementations and aspects of the specification will bedescribed with reference to details discussed below. The followingdescription and drawings are illustrative of the specification and arenot to be construed as limiting the specification. Numerous specificdetails are described to provide a thorough understanding of variousimplementations of the present specification. However, in certaininstances, well-known or conventional details are not described in orderto provide a concise discussion of implementations of the presentspecification.

The systems and methods described herein may be useful in the field ofneurosurgery, including oncological care, neurodegenerative disease,stroke, brain trauma and orthopedic surgery; however, persons of skillwill appreciate the ability to extend these concepts to other conditionsor fields of medicine. It should be noted that the surgical process isapplicable to surgical procedures for brain, spine, knee and any othersuitable region of the body.

Various apparatuses and processes will be described below to provideexamples of implementations of the system disclosed herein. Noimplementation described below limits any claimed implementation and anyclaimed implementations may cover processes or apparatuses that differfrom those described below. The claimed implementations are not limitedto apparatuses or processes having all of the features of any oneapparatus or process described below or to features common to multipleor all of the apparatuses or processes described below. It is possiblethat an apparatus or process described below is not an implementation ofany claimed subject matter.

Furthermore, numerous specific details are set forth in order to providea thorough understanding of the implementations described herein.However, it will be understood by those skilled in the relevant artsthat the implementations described herein may be practiced without thesespecific details. In other instances, well-known methods, procedures andcomponents have not been described in detail so as not to obscure theimplementations described herein.

In this specification, elements may be described as “configured to”perform one or more functions or “configured for” such functions. Ingeneral, an element that is configured to perform or configured forperforming a function is enabled to perform the function, or is suitablefor performing the function, or is adapted to perform the function, oris operable to perform the function, or is otherwise capable ofperforming the function.

It is understood that for the purpose of this specification, language of“at least one of X, Y, and Z” and “one or more of X, Y and Z” may beconstrued as X only, Y only, Z only, or any combination of two or moreitems X, Y, and Z (e.g., XYZ, XY, YZ, XZ, and the like). Similar logicmay be applied for two or more items in any occurrence of “at least one. . . ” and “one or more . . . ” language.

The terms “about”, “substantially”, “essentially”, “approximately”, andthe like, are defined as being “close to”, for example as understood bypersons of skill in the art. In some implementations, the terms areunderstood to be “within 10%,” in other implementations, “within 5%”, inyet further implementations, “within 1%”, and in yet furtherimplementations “within 0.5%”.

Referring to FIG. 1, a non-limiting example navigation system 100 isshown to support minimally invasive access port-based surgery. In FIG.1, a neurosurgeon 101 conducts a minimally invasive port-based surgeryon a patient 102 in an operating room (OR) environment. The navigationsystem 100 includes an equipment tower, tracking system, displays andtracked instruments to assist the surgeon 101 during the procedure. Anoperator 103 may also be present to operate, control and provideassistance for the navigation system 100.

Referring to FIG. 2, a diagram is shown illustrating components of anexample medical navigation system 200, according to non-limitingimplementations. The medical navigation system 200 illustrates a contextin which a surgical plan including equipment (e.g., tool and material)tracking, such as that described herein, may be implemented. The medicalnavigation system 200 includes, but is not limited to, one or moremonitors 205, 211 for displaying a video image, an equipment tower 201,and a mechanical arm 202, which supports an optical scope 204. Theequipment tower 201 may be mounted on a frame (e.g., a rack or cart) andmay contain a computer or controller (examples provided with referenceto FIGS. 3 and 6 below), planning software, navigation software, a powersupply and software to manage the mechanical arm 202, and trackedinstruments. In one example non-limiting implementation, the equipmenttower 201 may comprise a single tower configuration with dual displaymonitors 211, however other configurations may also exist (e.g., dualtower, single display, etc.). Furthermore, the equipment tower 201 mayalso be configured with a universal power supply (UPS) to provide foremergency power, in addition to a regular AC adapter power supply.

A patient's anatomy may be held in place by a holder. For example, in aneurosurgical procedure the patient's head may be held in place by ahead holder 217, and an access port 206 and an introducer 210 may beinserted into the patient's head. The introducer 210 may be trackedusing a tracking camera 213, which provides position information for thenavigation system 200. The tracking camera 213 may also be used to tracktools and/or materials used in the surgery, as described in more detailbelow. In one example non-limiting implementation, the tracking camera213 may comprise a 3D (three-dimensional) optical tracking stereocamera, similar to one made by Northern Digital Imaging (NDI),configured to locate reflective sphere tracking markers 212 in 3D space.In another example, the tracking camera 213 may comprise a magneticcamera, such as a field transmitter, where receiver coils are used tolocate objects in 3D space, as is also known in the art. Location dataof the mechanical arm 202 and access port 206 may be determined by thetracking camera 213 by detection of tracking markers 212 placed on thesetools, for example the introducer 210 and associated pointing tools.Tracking markers may also be placed on surgical tools or materials to betracked. The secondary display 205 may provide output of the trackingcamera 213. In one example non-limiting implementation, the output maybe shown in axial, sagittal and coronal views as part of a multi-viewdisplay.

As noted above with reference to FIG. 2, the introducer 210 may includetracking markers 212 for tracking. The tracking markers 212 may comprisereflective spheres in the case of an optical tracking system and/orpick-up coils in the case of an electromagnetic tracking system. Thetracking markers 212 may be detected by the tracking camera 213 andtheir respective positions are inferred by the tracking software.

As shown in FIG. 2, a guide clamp 218 (or more generally a guide) forholding the access port 206 may be provided. The guide clamp 218 mayoptionally engage and disengage with the access port 206 without needingto remove the access port 206 from the patient. In some examples, theaccess port 206 may be moveable relative to the guide clamp 218, whilein the guide clamp 218. For example, the access port 206 may be able toslide up and down (e.g., along the longitudinal axis of the access port206) relative to the guide clamp 218 while the guide clamp 218 is in aclosed position. A locking mechanism may be attached to or integratedwith the guide clamp 218, and may optionally be actuatable with onehand, as described further below. Furthermore, an articulated arm 219may be provided to hold the guide clamp 218. The articulated arm 219 mayhave up to six degrees of freedom to position the guide clamp 218. Thearticulated arm 219 may be lockable to fix its position and orientation,once a desired position is achieved. The articulated arm 219 may beattached or attachable to a point based on the patient head holder 217,or another suitable point (e.g., on another patient support, such as onthe surgical bed), to ensure that when locked in place, the guide clamp218 does not move relative to the patient's head.

Referring to FIG. 3, a block diagram is shown illustrating a control andprocessing unit 300 that may be used in the navigation system 200 ofFIG. 2 (e.g., as part of the equipment tower). In one examplenon-limiting implementation, control and processing unit 300 may includeone or more processors 302, a memory 304, a system bus 306, one or moreinput/output interfaces 308, a communications interface 310, and storagedevice 312. In particular, one or more processors 302 may comprise oneor more hardware processors and/or one or more microprocessors. Controland processing unit 300 may be interfaced with other external devices,such as tracking system 321, data storage device 342, and external userinput and output devices 344, which may include, but is not limited to,one or more of a display, keyboard, mouse, foot pedal, and microphoneand speaker. Data storage device 342 may comprise any suitable datastorage device, including, but not limited to a local and/or remotecomputing device (e.g. a computer, hard drive, digital media device,and/or server) having a database stored thereon. In the example shown inFIG. 3, data storage device 342 includes, but is not limited to,identification data 350 for identifying one or more medical instruments360 and configuration data 352 that associates customized configurationparameters with one or more medical instruments 360. Data storage device342 may also include, but is not limited to, preoperative image data 354and/or medical procedure planning data 356.

Although data storage device 342 is shown as a single device in FIG. 3,in other implementations, data storage device 342 may be provided asmultiple storage devices.

Medical instruments 360 may be identifiable using control and processingunit 300. Medical instruments 360 may be connected to and controlled bycontrol and processing unit 300, and/or medical instruments 360 may beoperated and/or otherwise employed independent of control and processingunit 300. Tracking system 321 may be employed to track one or more ofmedical instruments 360 and spatially register the one or more trackedmedical instruments 360 to an intraoperative reference frame. In anotherexample, a sheath may be placed over a medical instrument 360 and thesheath may be connected to and controlled by control and processing unit300.

Control and processing unit 300 may also interface with a number ofconfigurable devices, and may intraoperatively reconfigure one or moreof such devices based on configuration parameters obtained fromconfiguration data 352. Examples of devices 320, as shown in FIG. 3,include, but are not limited, one or more external image devices 322,one or more illumination devices 324, a robotic arm 305, one or moreprojection devices 328, and one or more displays 305, 311.

Aspects of the specification may be implemented via processor(s) 302and/or memory 304. For example, the functionalities described herein maybe partially implemented via hardware logic in processor 302 andpartially using the instructions stored in memory 304, as one or moreprocessing modules 370 and/or processing engines. Example processingmodules include, but are not limited to, user interface engine 372,tracking module 374, motor controller 376, image processing engine 378,image registration engine 380, procedure planning engine 382, navigationengine 384, and context analysis module 386. While the exampleprocessing modules are shown separately in FIG. 3, in one examplenon-limiting implementation the processing modules 370 may be stored inthe memory 304 and the processing modules may be collectively referredto as processing modules 370.

It is to be understood that the system is not intended to be limited tothe components shown in FIG. 3. One or more components of the controland processing unit 300 may be provided as an external component ordevice. In one example non-limiting implementation, navigation engine384 may be provided as an external navigation system that is integratedwith control and processing unit 300.

Some implementations may be implemented using processor 302 withoutadditional instructions stored in memory 304. Some implementations maybe implemented using the instructions stored in memory 304 for executionby one or more general purpose microprocessors. Thus, the specificationis not limited to a specific configuration of hardware and/or software.

While some implementations may be implemented in fully functioningcomputers and computer systems, various implementations are capable ofbeing distributed as a computing product in a variety of forms and arecapable of being applied regardless of the particular type of machine orcomputer readable media used to actually effect the distribution.

At least some aspects disclosed may be embodied, at least in part, insoftware. That is, the techniques may be carried out in a computersystem or other data processing system in response to its processor,such as a microprocessor, executing sequences of instructions containedin a memory, such as read only memory (ROM), volatile random accessmemory (RAM), non-volatile memory, cache and/or a remote storage device.

A computer readable storage medium, and/or a non-transitory computerreadable storage medium, may be used to store software and data which,when executed by a data processing system, causes the system to performvarious methods. The executable software and data may be stored invarious places including for example ROM, volatile RAM, non-volatilememory and/or cache. Portions of this software and/or data may be storedin any one of these storage devices.

Examples of computer-readable storage media include, but are not limitedto, recordable and non-recordable type media such as volatile andnon-volatile memory devices, ROM, RAM, flash memory devices, floppy andother removable disks, magnetic disk storage media, optical storagemedia (e.g., compact discs (CDs), digital versatile disks (DVDs), etc.),among others. The instructions may be embodied in digital and analogcommunication links for electrical, optical, acoustical and/or otherforms of propagated signals, such as carrier waves, infrared signals,digital signals, and the like. The storage medium may comprise theinternet cloud, storage media therein, and/or a computer readablestorage medium and/or a non-transitory computer readable storage medium,including, but not limited to, a disc.

At least some of the methods described herein are capable of beingdistributed in a computer program product comprising a computer readablemedium that bears computer usable instructions for execution by one ormore processors, to perform aspects of the methods described. The mediummay be provided in various forms such as, but not limited to, one ormore diskettes, compact disks, tapes, chips, USB (Universal Serial Bus)keys, external hard drives, wire-line transmissions, satellitetransmissions, internet transmissions or downloads, magnetic andelectronic storage media, digital and analog signals, and the like. Thecomputer useable instructions may also be in various forms, includingcompiled and non-compiled code.

According to one aspect of the present application, one purpose of thenavigation system 200, which may include control and processing unit300, is to provide tools to a surgeon and/or a neurosurgeon that willlead to the most informed, least damaging neurosurgical operations. Inaddition to removal of brain tumours and intracranial hemorrhages (ICH),the navigation system 200 may also be applied to a brain biopsy, afunctional/deep-brain stimulation, a catheter/shunt placement procedure,open craniotomies, endonasal/skull-based/ENT, spine procedures, andother parts of the body such as breast biopsies, liver biopsies, etc.While several examples have been provided, aspects of the presentspecification may be applied to other suitable medical procedures.

Attention is next directed to FIG. 4 which depicts a non-limitingexample of a port-based brain surgery procedure using a video scope. InFIG. 4, operator 404, for example a surgeon, may align video scope 402to peer down port 406. Video scope 402 may be attached to an adjustablemechanical arm 410. Port 406 may have a tracking tool 408 attached to itwhere tracking tool 408 is tracked by a tracking camera of a navigationsystem.

Even though the video scope 402 may comprise an exoscope and/or amicroscope, these devices introduce optical and ergonomic limitationswhen the surgical procedure is conducted over a confined space andconducted over a prolonged period such as the case with minimallyinvasive brain surgery.

FIG. 5 illustrates the insertion of an access port 12 into a human brain10, in order to provide access to interior brain tissue during a medicalprocedure. In FIG. 5, access port 12 is inserted into a human brain 10,providing access to interior brain tissue. Access port 12 may include,but is not limited to, instruments such as catheters, surgical probes,and/or cylindrical ports such as the NICO BrainPath®. Surgical tools andinstruments may then be inserted within a lumen of the access port 12 inorder to perform surgical, diagnostic or therapeutic procedures, such asresecting tumors as necessary. However, the present specificationapplies equally well to catheters, DBS needles, a biopsy procedure, andalso to biopsies and/or catheters in other medical procedures performedon other parts of the body.

In the example of a port-based surgery, a straight and/or linear accessport 12 is typically guided down a sulci path of the brain. Surgicalinstruments and/or surgical tools would then be inserted down the accessport 12.

Attention is next directed to FIG. 6, FIG. 7, and FIG. 8 each of whichdepict a side schematic view of an example exoscope 601 with enhanceddepth of field imaging, that could be used with the access port 12and/or in open case surgery, for example to image a sample 602, asdepicted a human brain (such as the human brain 10).

The exoscope 601 comprises a first set of optical devices 611 and asecond set of optical devices 612. The first set of optical devices 611form a first optical path 621 having a fixed optical path length and afixed image plane, and the second set of optical devices 612 form asecond optical path 622 having a variable optical path length and avariable image plane (e.g. see FIG. 9, described below).

While in FIG. 6, FIG. 7, and FIG. 8, the optical paths 621, 622 are notfocused directly at a surface of the sample 602, it is understood thatthis depiction is for clarity only and the optical paths 621, 622 aregenerally focused at the surface of the sample 602.

As explained in detail below, the second set of optical devices 612includes at least one variable device configured to change a length ofthe variable optical path length of the second set of optical devices612 and a position of the variable image plane relative to the fixedimage plane of the first set of optical devices 611.

For clarity, FIG. 6 depicts the first optical path 621 of the first setof optical devices 611, FIG. 7 depicts a second optical path 622-1 ofthe second set of optical devices 612 in a first configuration of thevariable device of the second set of optical devices 612, and FIG. 8depicts a further second optical path 622-2 of the second set of opticaldevices 612 in a second configuration of the variable device of thesecond set of optical devices 612. The two second optical paths 622-1,622-2 will be interchangeably referred to, collectively as the secondoptical paths 622 and, generically, as the second optical path 622.

Furthermore, as depicted, a center dashed line of each of the opticalpaths 621, 622 show a general path through each of the sets of opticaldevices 611, 612, while the two dashed outer lines of each of theoptical paths (e.g. on either side of the center dashed line) generallyshow focusing and the like by lenses, and the like, of each of the setsof optical devices 611, 612. Hence, together, the three lines of each ofthe optical paths 621, 622, show the general behavior of light and/orimages via the optical paths 621, 622.

The components of the exoscope 601 will next be described with referenceto any of FIG. 6, FIG. 7 and FIG. 8, though a description of the firstoptical path 621 is with reference to FIG. 6 and a description of theoptical paths 622 is with reference to FIG. 7 and FIG. 8.

The first set of optical devices 611 comprises a first image detector631 configured to acquire a first image at the fixed image plane (e.g.see FIG. 9, described below) of the first set of optical devices 611.Similarly, the second set of optical devices 612 comprises a secondimage detector 632 configured to acquire a second image at the variableimage plane of the second set of optical devices 612. Each of the imagedetectors 631, 632 may comprise a charge-coupled device (CCD) and thelike, though any type of suitable image detector is within the scope ofthe present specification including, but not limited to, image detectorsthat are detect specific wavelengths and/or wavelength ranges; forexample, one or both of the image detectors 631, 632 may be configuredto detect fluorescence in the sample 602. In these examples, one imagedetector 631, 632 may be configured to detect fluorescence, and theother image detector 632, 631 may be configured to detect images inwavelength ranges visible to a human vision system (e.g. such as whitelight images and/or color images) in which an overlay between a whitelight image and a fluorescence image could be formed. In some of theseexamples, the image detector 631 configured to acquire images at thefixed image plane may be used to acquire white light images, while theimage detector 632 configured to acquire images at the variable imageplane may be used to acquire fluorescence images (e.g. since afluorescence image may not provide as many resolution details a as whitelight image, and the images at the variable image plane may be slightlyout of focus and/or more regions in the images at the variable imageplane may be slightly out of focus as compared to the images at thefixed image plane). Hence, a person of skill in the art understands thatthe first image detector 631 and the second image detector 632 may havedifferent respective wavelength sensitivity ranges.

The first set of optical devices 611 are generally configured to imagethe sample 602 onto the image detector 631. As depicted, the first setof optical devices 611 further comprises a focusing lens 641, one ormore zoom lenses 642 and an objective lens 643. However, otherconfigurations of optical devices are within the scope of the presentspecification and the first set of optical devices 611 may include otherlenses and/or different lenses, mirrors, prisms and/or any type ofoptical device for imaging the sample 602 onto the image detector 631.

In general images acquired by the first image detector 631 are focusedonto the first image detector 631 by the focusing lens 641, the zoomlens 642 provides a fixed optical zoom for the exoscope 601, and theobjective lens 643 acquires images in an image plane at least partiallydefined by the focal length of the objective lens 643.

Similarly, the second set of optical devices 612 are generallyconfigured to image the sample 602 onto the image detector 632. Asdepicted, the second set of optical devices 612 further comprises afocusing lens 651 and the one or more zoom lenses 642 and the objectivelens 643.

In general images acquired by the second image detector 632 are focusedonto the second image detector 632 by the focusing lens 651.

Other configurations of optical devices are within the scope of thepresent specification and the second set of optical devices 612 mayinclude other lenses and/or different lenses, mirrors, prisms and/or anytype of optical device for imaging the sample 602 onto the imagedetector 632.

However, the second set of optical devices 612 further comprises, atleast one variable device 655 configured to change a length of thevariable optical path length (e.g. of the second optical path 622) and aposition of the variable image plane relative to the fixed image planeof the first set of optical devices 611. The variable device 655 maycomprise one or more of varifocal lens having a variable focal length, aliquid-based varifocal lens configured to change between a parallelplane mode and a lens mode, a moveable lens and an apparatus for movingthe moveable lens along the second optical path 622, an apparatus formoving the second image detector 632 along the second optical path, andthe like.

However, with reference to FIG. 7 and FIG. 8, as depicted, the at leastone variable device 655 comprises a varifocal lens having a variablefocal length for example by changing a thickness and/or curvature of thevarifocal lens. Hence, by changing the focal length of the varifocallens, the focal length changes and hence the optical length of thesecond optical path 622 changes.

In some examples, the varifocal lens may include a bendable and/ormalleable and/or deformable portion which, when deformed (e.g. via avoicecoil, and the like), and the like, changes the focal length.

However, as specifically depicted in FIG. 7 and FIG. 8, the at least onevariable device 655 may comprise a liquid-based varifocal lensconfigured to change between a parallel plane mode and a lens mode.

For example, in FIG. 7 (and FIG. 6), the at least one variable device655 is depicted as a liquid-based varifocal lens in a parallel planemode, as the shape of the liquid-based varifocal lens is a parallelplane with a center of the second optical path 622 being normal to thefaces of the liquid-based varifocal lens.

However, in FIG. 8, the at least one variable device 655 is depicted asa liquid-based varifocal lens in a lens mode; for example, in FIG. 8, anelectrical current may have been applied to a voice coil contained in aliquid-based varifocal lens to change the shape from a parallel plane(as in FIG. 7) to a lens.

To contrast the changing shape of the liquid-based varifocal lens (e.g.the at least one variable device 655), in FIG. 7, the shape of theliquid-based varifocal lens in the parallel plane mode is depicted insolid lines and the shape of the liquid-based varifocal lens in the lensmode is depicted in dashed lines; similarly, in FIG. 8, the shape of theliquid-based varifocal lens in the lens mode is depicted in solid linesand the shape of the liquid-based varifocal lens in the parallel planemode is depicted in dashed lines.

It is understood by persons of skill in the art that the focal length ofthe least one variable device 655 depicted in FIG. 7 is infinite (e.g.such that the focusing lens 651, the zoom lens 642 and the objectivelens 643 define the optical path length of the second optical path 622-1in FIG. 7), whereas the focal length of the least one variable device655 depicted in FIG. 8 is not infinite (e.g. such that focusing lens651, the least one variable device 655, the zoom lens 642 and theobjective lens 643 define the optical path length of the second opticalpath 622-2 in FIG. 8). Hence, by varying the focal length of the leastone variable device 655, the length of the second optical path 622 ofthe second set of optical devices 612 may be varied, as well as aposition of an image plane of the second optical path 622.

In some examples, the focal length of the least one variable device 655may be smoothly varied and/or varied in an analog fashion, and hence alength of the optical path 622 of the second set of optical devices 612may be smoothly varied to select a length of the length of the secondoptical path 622. For example, if the lens mode of the liquid-basedvarifocal lens in FIG. 8 shows a maximum amount of liquid that may be inthe liquid-based varifocal lens, and if the parallel plane mode of theliquid-based varifocal lens in FIG. 7 shows a minimum amount of liquidthat may be in the liquid-based varifocal lens, a length of the secondoptical path 622 of the second set of optical devices 612 may besmoothly varied between the two modes and two focal lengths etc., and bychanging the amount of liquid in the liquid-based varifocal lens.

Control of the least one variable device 655 will be described in moredetail below.

As will now be apparent, the first set of optical devices 611 and thesecond set of optical devices 612 share the zoom lens 642 and theobjective lens 643 and an overlapping portion of the optical paths 621,622 each include the shared lenses 642, 643. However, to ensure thatrespective light from each of the optical paths 621, 622 are directed tothe respective image detectors 631, 632, the exoscope 601 furthercomprises a beamsplitter 660 positioned in both the first optical path621 and the second optical path 622, the beamsplitter 660 configured to:combine the first optical path 621 and the second optical path 622between the beamsplitter 660 and both the fixed image plane of the firstset of optical devices 611 and the variable image plane of the secondset of optical devices 622; and direct respective light from each of thefirst optical path 621 and the second optical path 622 respectivelytowards the first image detector 631 and the second image detector 632.

As depicted, the portion of the second optical path 622 that does notoverlap with the first optical path 621 is at about 90° to the firstoptical path 621. Hence, the beamsplitter 660 is at 45° to each of theoptical paths 621, 622.

For example, the beamsplitter 660 may comprise a 50/50 beam splitter andthe like. However, when each of the image detectors 631, 632 are toimage different wavelength ranges, the beamsplitter 660 may comprise anoptical filter, such as a dichroic filter, and the like, configured totransmit wavelengths to be imaged by the first image detector 631 andreflect wavelengths to be imaged by the second image detector 632.

Hence, in general, the combination of the first set of optical devices611, the second set of optical devices 612, the beamsplitter 660 and theimage detectors 631, 632 produce at least two images of the sample 602:a first image produced by the first set of optical devices 611 and thefirst image detector 631, and a second image produced by the second setof optical devices 612 and the second image detector 632. As the atleast one variable device 655 may be controlled to change a length ofthe optical path length of the second optical path 622, and hence alsochange a position of the image plane of the second optical path 622relative to the fixed image plane of the first optical path 621, thesecond image generally has a different depth of focus than the firstimage. These images may be combined to produce an image with an extendeddepth of field that may be the combination of the depths of field of thetwo images.

For example, as depicted, the exoscope 601 further comprises: a displaydevice 670 and a controller 680. The display device 670 may be one ofmore of the displays 305, 311; however, the display device 670 may be acomponent of a surgical computer, a heads-up display (HUD) device, andthe like. The controller 680 may comprise one or more hardwareprocessors, one or more microcontrollers, one or more microprocessor,and the like including, but not limited to, the one or more processors302. As depicted, the controller 302 is in communication with thedisplay device 670, the image detectors 631, 632 and the at least onevariable device 655 via respective wired and/or wireless links depictedas arrows in the figures.

In general, the controller 680 is configured to: control the at leastone variable device 655 to change the length of the variable opticalpath length of the second set of optical devices 612 and the position ofthe variable image plane of the second set of optical devices 612relative to the fixed image plane of the first set of optical devices611; control the first image detector 631 to acquire a first image atthe fixed image plane; control the second image detector 632 to acquirea second image at the variable image plane; generate a combined image ofthe first image and the second image; and control the display device 670to render the combined image.

For example, a surgeon operating on a patient may interact with an inputdevice (such as a point device, a graphic user interface at the displaydevice 670, and the like) in communication with the controller 680, tocause the controller 680 to control the at least one variable device 655to change the length of the variable optical path length of the secondset of optical devices 612 and the position of the variable image planeof the second set of optical devices 612 relative to the fixed imageplane of the first set of optical devices 611. For example, the surgeonmay interact with the input device to select an image plane of thesecond set of optical devices 612. While not depicted, it is understoodby persons of skill in the art that the at least one variable device 655comprises suitable devices to control the focal length, and the like(e.g. a deformable membrane controllable with an electrically controlledvoice coil and the like) which communicate with the controller 680 tochange the length of the variable optical path length of the second setof optical devices 612 and the position of the variable image plane ofthe second set of optical devices 612 relative to the fixed image planeof the first set of optical devices 611. Once the variable image planeis selected, the controller 680 acquires images from the image detectors631, 632, combines the images and controls the display device 670 torender a combined image. In some examples, described below, the displaydevice 670 may be alternatively controlled to render one or more of theimages produced by the image detectors 631, 632 and/or the combinedimage (e.g. see FIG. 10).

As depicted, the exoscope 601 includes a housing 699 which may beconfigured to be held by an arm of a surgical system, for example one ormore of arms 202, 410. Indeed, the video scope 402 may be adapted toinclude the exoscope 601. The housing 699 may include one or moreapertures and/or windows and the like adjacent the objective lens 643,as well as electrical connections and the like.

Attention is next directed to FIG. 9 which schematically depicts thesample 602, the objective lens 643 and the three optical paths 621,622-1, 622-2 as they focus at the sample 602, as well as respectiveimage planes 901, 902-1, 902-2 located at a focal length of the threeoptical paths 621, 622-1, 622-2. While in FIG. 9, the image planes 901,902-1, 902-2 are not located directly at a surface of the sample 602, itis understood that this depiction is for clarity only and the imageplanes 901, 902-1, 902-2 are located at the surface of the sample 602.

The image plane 901 is generally in a fixed position as the optical path621 is fixed. Hence, the image plane 901 may interchangeably be referredto as the fixed image plane 901 of the first set of optical devices 611and/or the first optical path 621.

However, depending on a length of the second optical path 622 (e.g. ascontrolled via the controller 680 controlling the variable device 655),the image plane of the second optical path 622 may change between theimage plane 902-1 (e.g. when the second optical path 622 is set to thesecond optical path 622-1) and the image plane 902-2 (e.g. when thesecond optical path 622 is set to the second optical path 622-2). Hence,the image planes 902-1, 902-2 may interchangeably be referred to as thevariable image plane 902 of the second set of optical devices 612 and/orthe second optical path 622.

Hence a first image acquired by the first image detector 631 at theimage plane 901 may be combined with a second image acquired by thesecond image detector 632 at one or more of the image planes 902-1,902-2 and/or image planes therebetween. In other words, in someexamples, the image plane of the second optical path 622 may be changedto any image plane between the image planes 902-1, 902-2.

Attention is next directed to FIG. 10 which depicts a schematic blockdiagram of the controller 680, the image detectors 631, 632, the atleast one variable device 655 and the display device 670 of the exoscope601 (e.g. as depicted in FIGS. 6-8); while not all the components of theexoscope 601 are depicted in FIG. 10, they are nonetheless assumed to bepresent.

As depicted, the controller 680 comprises two splitter modules 1001,1002, the first splitter module 1001 in communication with the firstimage detector 631, and the second splitter module 1002 in communicationwith the second image detector 632 via a correction module 1003. Thecorrection module 1003 is configured to correct images from the secondimage detector 632 for magnification, distortion and spatial offsetsrelative to the images from the first image detectors 631. For example,the images produced by each of the image detectors 631, 632 may havedifferences in magnification, and relative position of features of thesample 602, and the correction module 1003 corrects for thesedifferences based, for example, on differences in the images previouslydetermined during a calibration step. Alternatively, and/or in additionto the correction module 1003, the first splitter module 1001 may be incommunication with the first image detector 631 via a similar correctionmodule. However, the correction module 1003, and the like, may beoptional.

As depicted, the controller 680 further comprises a variable devicecontrol module 1005 configured to communicate with components of the atleast one variable device 655 to change the length of the second opticalpath 622. The variable device control module 1005 may be controlled byan input device, as described above. For example, when the at least onevariable device 655 comprises a liquid-based varifocal lens, thevariable device control module 1005 may control an amount of liquid inthe varifocal lens. Similar, when the at least one variable device 655comprises apparatus moving the second image detector 632 and/or amoveable lens, the variable device control module 1005 may control theposition of the second image detector 632 and/or the moveable lens.

The variable device control module 1005 may hence control at least onevariable device 655 to select an image plane 902 (e.g. as depicted inFIG. 9), and each of the splitter modules 1001, 1002 may communicatewith the respective image detectors 631, 632 to produce a respectiveimage 1011, 1012 (e.g. each having a different depth of field) asdescribed above, the image 1012 optionally corrected using thecorrection module 1003.

Each of the splitter modules 1001, 1002 communicate with an image fusermodule 1013 and a video switch matrix 1015. The image fuser module 1013receives both the images 1011, 1012 and produces a combined image 1021of the images 1011, 1012 (e.g. the image fuser module 1013 combinesand/or “fuses” the images 1011, 1012 to produce the combined image1021). As described above, the controller 680 may be configured tocorrect at least one of the first image 1011 and the second image 1012prior to combining the first image 1011 and the second image 1012 tocorrect for one or more of magnification and spatial offsets.

The combined image 1021 has an extended depth of field as compared tothe images 1011, 1012. For example, the image fuser module 1013 maycombine in-focus regions of the first image 1011 with in-focus regionsof the second image 1012 to produce the combined image 1021, which mayhence generally include more in-focus regions than either of the images1011, 1012 alone.

The image fuser module 1013 is also in communication with a video switchmatrix 1015. The video switch matrix 1015 is in communication with thedisplay device 670. The video switch matrix 1015 receives both theimages 1011, 1012 and the combined image 1021; the video switch matrix1015 may be used to selectively switch between one of the images 1011,1012, 1021 for rendering at the display device 670, for example undercontrol of graphic user interface and/or an input device operated by asurgeon and the like. In yet further examples, the video switch matrix1015 may be used to rapidly switch between the images 1011, 1012 forrendering at the display device 670, for example at frame rate where ahuman eye may combine the images 1011, 1012 into apseudo-three-dimensional image, such frame rates greater than or equalto about 20 frames per second.

Hence, the controller 680 may be further configured to control thedisplay device 670 to change between rendering the: first image 1011,the second image 1012 and the combined image 1021.

While the exoscope 601 has been described with respect to specificcomponents, the exoscope 601 may be adapted to include other types ofcomponents.

For example, attention is next directed to FIG. 11 which depicts anexoscope 1101 that is substantially similar to the exoscope 601 withlike components having like numbers. However, in contrast to theexoscope 601, at the exoscope 1101, each of first set of optical devices611 and the second set of optical devices 612 have been adapted toinclude a respective optical filter 1111, 1112 for filtering respectivelight of one or more of the first image 1011 (e.g. as in FIG. 10) andthe second image 1012 (e.g. as in FIG. 10). While each of the opticalfilters 1111, 1112 are located adjacent a respective image detector 631,632, the optical filters 1111, 1112 may be located in any portion of therespective optical paths 621, 622 that do not overlap.

While FIG. 11 depicts two optical filters 1111, 1112 at the exoscope1101, the exoscope 1101 may comprise only one of the optical filters1111, 1112. Further, the optical filters 1111, 1112 may transmit thesame wavelengths (e.g. have the same bandwidth) or different wavelengths(e.g. have different bandwidths). When the optical filters 1111, 1112have the same bandwidth, the optical filters 1111, 1112 may be replacedwith a single optical filter in a portion of the optical paths 621, 622(see FIGS. 6-8, for example) that overlap.

Further alternatives for the at least one variable device 655 are alsowithin the scope of the present specification. For example, attention isnext directed to FIG. 12 which depicts an exoscope 1201 that issubstantially similar to the exoscope 601 with like components havinglike numbers. However, in contrast to the exoscope 601, at the exoscope1201, the liquid-based varifocal lens of the at least one variabledevice 655 has been replaced with at least one variable a variabledevice 1252 comprising a moveable lens 1253 and an apparatus for movingthe moveable lens 1253 along the second optical path 622 (e.g. as bestdepicted in FIG. 7 and FIG. 8). For example, as depicted, the apparatusfor moving the moveable lens 1253 along the second optical path 622comprises a motor 1254, such as a stepper motor and the like, and atrack 1255 (e.g. as depicted on two sides of the moveable lens 1253)and/or a rack-and-pinion apparatus, and the like. The motor 1254generally moves the moveable lens 1253 along the track 1255 undercontrol of the controller 680 (e.g. using the variable device controlmodule 1005). Hence, with reference to FIG. 9, the image plane 902 ofthe second optical path 622 may be varied by moving the moveable lens1253.

Further alternatives for the at least one variable device 655 are alsowithin the scope of the present specification. For example, attention isnext directed to FIG. 13 which depicts an exoscope 1301 that issubstantially similar to the exoscope 601 with like components havinglike numbers. However, in contrast to the exoscope 601, at the exoscope1301, the liquid-based varifocal lens of the at least one variabledevice 655 has been replaced with at least one variable a variabledevice 1352 comprising an apparatus for moving the second image detector632 along the second optical path 622 (as best depicted in FIG. 7 andFIG. 8). For example, as depicted, the apparatus for moving the secondimage detector 632 along the second optical path 622 comprises a motor1354, such as a stepper motor and the like, and a track 1355 (e.g. asdepicted on two sides of the second image detector 632) and/or arack-and-pinion apparatus, and the like. The motor 1354 generally movesthe second image detector 632 along the track 1355 under control of thecontroller 680 (e.g. using the variable device control module 1005).Hence, with reference to FIG. 9, the image plane 902 of the secondoptical path 622 may be varied by moving the second image detector 632.

Indeed, any of the variable devices, 655, 1252, 1352 and/or any othervariable devices for changing a length of the optical path 622 may becombined in an exoscope. For example, components and functionality formoving the second image detector 632 and/or moving the moveable lens1253 and/or changing the focal length of the liquid-based varifocal lens(e.g. the variable device 655) may be combined in one exoscope. Indeed,in some examples, components and functionality for moving the secondimage detector 632 and one of moving the moveable lens 1253 and changingthe focal length of the liquid-based varifocal lens (e.g. the variabledevice 655) may be combined to assist in focusing the second image 1012on the second image detector 632. Indeed, in some examples, the focusinglens 651 may also be moveable to assist in focusing the second image1012 on the second image detector 632.

In some examples, exoscopes described herein may be combined intothree-dimensional image detectors. For example, attention is nextdirected to FIG. 14 which schematically depicts a three-dimensionalimage detector 1401, that includes the exoscope 601 (e.g. a firstexoscope) and a second exoscope 1411 that is substantially similar tothe exoscope 601. While the components of the exoscopes 601, 1411 arenot numbered, the components of each of the exoscopes 601, 1411 aresimilar to as described above with respect to FIG. 6, FIG. 7 and FIG. 8.However, the exoscopes 601, 1411 are arranged relative to each other toacquire respective combined images of the sample 602, each of therespective combined images from each of the exoscopes 601, 1411 viewabletogether (e.g. respectively by a left eye and a right eye of a viewer)as a three-dimensional image.

Hence, the first set of optical devices 611, the second set of opticaldevices 612, the image detectors 631, 632, and the beamsplitter 660(e.g. of the exoscope 601) comprise a first channel of thethree-dimensional image detector 1401, the three-dimensional imagedetector 1401 further comprising a second channel (e.g. produced by thesecond exoscope 1411) similar to the first channel, each of the firstchannel and the second channel configured to produce respective imagesof a three-dimensional image.

Furthermore, the three-dimensional image detector 1401 comprises adisplay device 1470 and a controller 1480 each respectively similar tothe display device 607 and the controller 680, however the displaydevice 1470 is adapted to render three-dimensional images and thecontroller 1480 is configured to produce the three-dimensional images,for example by producing a respective combined image for each of theexoscopes 601, 1411, as described above. Hence, the controller 1480 isin communication with respective first image detectors (e.g. the firstimage detector 631) and respective second image detectors (e.g. thesecond image detector 632) at each of the exoscopes 601, 1411; while notdepicted, the controller 1480 may be further configured to controlrespective at least one variable devices (e.g. the at least one variabledevice 652) at each of the exoscopes 601, 1411.

As depicted, each of the exoscopes 601, 1411 comprise respectiveoptional optical filter 1451, 1452, for example in the portion of eachexoscope 601, 1411 having a combined optical path, though the eachexoscope 601, 1411 may include optical filters similar to the opticalfilters 1111, 1112 (e.g. as depicted in FIG. 11). The optical filters1451, 1452 may have the same or different bandwidths, for example forfiltering light from the sample 602 for three-dimensional fluorescenceimaging and/or for three-dimensional fluorescence-white light combinedimages (for example, each optical filter 1451, 1452 could have aslightly different bandwidth).

Furthermore the controller 1480 is generally configured to control theat least one variable device of each of the first exoscope 601 and thesecond exoscope 1411 to change the length of the variable optical pathlength and the position of the variable image plane relative to thefixed image plane; control the first image detector of each of the firstexoscope 601 and the second exoscope 1411 to acquire the first image atthe fixed image plane; control the second image detector of each of thefirst exoscope 601 and the second exoscope 1411 to acquire the secondimage at the variable image plane; generate a combined image of thefirst image and the second image of each of the first exoscope 601 andthe second exoscope 1411; and control the display device 1470 to renderthe combined image of each of the first exoscope 601 and the secondexoscope 1411 as a stereoscopic image 1489.

As depicted, the three-dimensional image detector 1401 includes ahousing 1499 which may be configured to be held by an arm of a surgicalsystem, for example one or more of arms 202, 410. Indeed, the videoscope 402 may be adapted to include the three-dimensional image detector1401.

While present examples have been described with respect to varying anoptical path length and/or an image plane via one or more of a varifocallens, a liquid-based varifocal lens, a moveable sensor, and a moveablelens, other types of suitable devices for varying an optical path lengthand/or an image plane are within the scope of the present specification.For example, with reference to FIG. 6, the at least one variable device655 may alternatively include a moveable plenoptic lens (e.g. an arrayof microlenses with different regions having different focal lengths, aposition of the regions with respect to the second image sensor 632controlled a via one or more stepper motors), and/or an opticwheel (e.g.a plurality of lenses on wheel with different lenses having differentfocal lengths, a position of the plurality of lenses with respect to thesecond image sensor 632 controlled a via one or more stepper motors),and the like.

While present examples are described with respect to exoscopes, at leastthe optical components described herein may be adapted for use in anendoscope and/or a surgical microscope. For example, the sets of opticaldevices 611, 612 (and similarly optical devices of the exoscope 1411)may be adapted for use in an endoscope and/or a surgical microscope,and/or the housings 699, 1499 may be replaced with and/or adapted forendoscope housings and/or a surgical microscope housings.

Provided herein is an exoscope with extended depth of field with twooptical paths, each of which include a respective image detector, and inwhich a variable device is used to change an optical path length of oneof the optical paths to extend the depth of field of a combined imageproduced from respective images of the image detectors, the depth offield of the combined image extended with respect to the depths of fieldof each of the individual images of the image detectors.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

What is claimed is:
 1. An exoscope comprising: a first set of opticaldevices, forming a first optical path having a fixed path length and afixed image plane, including a first image detector configured toacquire a first image at the fixed image plane; a second set of opticaldevices, forming a second optical path having a variable optical pathlength and a variable image plane adjacent the fixed image plane of thefirst set of optical devices, the second set of optical devicesincluding: a second image detector configured to acquire a second imageat the variable image plane; and at least one variable device configuredto change a length of the variable optical path length and a position ofthe variable image plane relative to the fixed image plane; abeamsplitter positioned in both the first optical path and the secondoptical path, the beamsplitter configured to: combine the first opticalpath and the second optical path between the beamsplitter and both thefixed image plane and the variable image plane; and direct respectivelight from each of the first optical path and the second optical pathrespectively towards the first image detector and the second imagedetector; a display device; and a controller configured to: control theat least one variable device to change the length of the variableoptical path length and the position of the variable image planerelative to the fixed image plane; control the first image detector toacquire the first image at the fixed image plane; control the secondimage detector to acquire the second image at the variable image plane;generate a combined image of the first image and the second image; andcontrol the display device to render the combined image.
 2. The exoscopeof claim 1, wherein the at least one variable device comprises aliquid-based varifocal lens configured to change between a parallelplane mode and a lens mode.
 3. The exoscope of claim 1, wherein the atleast one variable device comprises a varifocal lens having a variablefocal length.
 4. The exoscope of claim 1, wherein the at least onevariable device comprises a moveable lens and an apparatus for movingthe moveable lens along the second optical path.
 5. The exoscope ofclaim 1, wherein the at least one variable device comprises an apparatusfor moving the second image detector along the second optical path. 6.The exoscope of claim 1, wherein the first image detector and the secondimage detector have different respective wavelength sensitivity ranges.7. The exoscope of claim 1, wherein the controller is further configuredto control the display device to change between rendering the: firstimage, the second image and the combined image.
 8. The exoscope of claim1, wherein one or more of the first optical path and the second opticalpath include an optical filter for filtering respective light of one ormore of the first image and the second image.
 9. The exoscope of claim1, wherein the controller is further configured to correct at least oneof the first image and the second image prior to combining the firstimage and the second image to correct for one or more of magnificationand spatial offsets.
 10. The exoscope of claim 1, further comprising athree-dimensional image detector, wherein the first set of opticaldevices, the second set of optical devices, the first image detector,the second image detector, and the beamsplitter comprise a first channelof the three-dimensional image detector, the three-dimensional imagedetector further comprising a second channel similar to the firstchannel, each of the first channel and the second channel configured toproduce respective images of a three-dimensional image.
 11. The exoscopeof claim 10, wherein each of the first channel and the second channelinclude a respective optical filter.
 12. A three-dimensional imagedetector comprising: a first exoscope and a second exoscope, each of thefirst exoscope and the second exoscope comprising: a first set ofoptical devices, forming a first optical path having a fixed path lengthand a fixed image plane, including a first image detector configured toacquire a first image at the fixed image plane; a second set of opticaldevices, forming a second optical path having a variable optical pathlength and a variable image plane adjacent the fixed image plane of thefirst set of optical devices, the second set of optical devicesincluding: a second image detector configured to acquire a second imageat the variable image plane; and at least one variable device configuredto change a length of the variable optical path length and a position ofthe variable image plane relative to the fixed image plane; abeamsplitter positioned in both the first optical path and the secondoptical path, the beamsplitter configured to: combine the first opticalpath and the second optical path between the beamsplitter and both thefixed image plane and the variable image plane; and direct respectivelight from each of the first optical path and the second optical pathrespectively towards the first image detector and the second imagedetector; a display device; and a controller configured to: control theat least one variable device of each of the first exoscope and thesecond exoscope to change the length of the variable optical path lengthand the position of the variable image plane relative to the fixed imageplane; control the first image detector of each of the first exoscopeand the second exoscope to acquire the first image at the fixed imageplane; control the second image detector of each of the first exoscopeand the second exoscope to acquire the second image at the variableimage plane; generate a combined image of the first image and the secondimage of each of the first exoscope and the second exoscope; and controlthe display device to render the combined image of each of the firstexoscope and the second exoscope as a stereoscopic image.
 13. Thethree-dimensional image detector of claim 12, wherein the at least onevariable device of each of the first exoscope and the second exoscopecomprises a liquid-based varifocal lens configured to change between aparallel plane mode and a lens mode.
 14. The three-dimensional imagedetector of claim 12, wherein the at least one variable device of eachof the first exoscope and the second exoscope comprises a varifocal lenshaving a variable focal length.
 15. The three-dimensional image detectorof claim 12, wherein the at least one variable device of each of thefirst exoscope and the second exoscope comprises a moveable lens and anapparatus for moving the moveable lens along the second optical path.16. The three-dimensional image detector of claim 12, wherein the atleast one variable device of each of the first exoscope and the secondexoscope comprises an apparatus for moving the second image detectoralong the second optical path.
 17. The three-dimensional image detectorof claim 12, wherein the first image detector and the second imagedetector of each of the first exoscope and the second exoscope havedifferent respective wavelength sensitivity ranges.
 18. Thethree-dimensional image detector of claim 12, wherein one or more of thefirst optical path and the second optical path of each of the firstexoscope and the second exoscope include an optical filter for filteringrespective light of one or more of the first image and the second image.19. The three-dimensional image detector of claim 12, wherein thecontroller is further configured to correct at least one of the firstimage and the second image of each of the first exoscope and the secondexoscope prior to combining the first image and the second image of eachof the first exoscope and the second exoscope to correct for one or moreof magnification and spatial offsets.
 20. The three-dimensional imagedetector of claim 12, wherein the first set of optical devices, thesecond set of optical devices, the first image detector, the secondimage detector, and the beamsplitter of each of the first exoscope andthe second exoscope respectively comprise a first channel and a secondchannel similar to the first channel, and each of the first channel andthe second channel include a respective optical filter.